How to Replace an programming audi key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge, above the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49), Audi A1 keys then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using an uncolored wire. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors in the right way.

If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).

It can be a bit difficult to test as there are different pins on the connector and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is fully functional, it should read about 1000 ohms. If you're having issues with this sensor, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive decrease in power. It was like the engine was running out of gas. Or my injectors weren't firing. I pulled out the spark plugs this morning, three were soaked with gasoline and the 4th was dry. When i crank the engine, there are no sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th one stays shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. I think the issue is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and Audi a1 keys it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I don't know what to do. I feel like i've pretty much eliminated everything else. However, i'm afraid that I may have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

Some of the signs of a failing G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. If you have any of these issues it is likely that your sensor is deteriorating and should be replaced. The good thing is that they are very cheap and easy to find particularly in the case of a Bosch sensor, which is what we have. If you prefer, GM's version of this component is an excellent choice.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous problems in your vehicle. It's an essential component of your audi replacement key cost uk's transmission, because it communicates to the ECU about how the car's crankshaft is turning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU uses this signal to regulate the amount of fuel and boost, as well as timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is the same across the Audi A1 keys 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU, so you might find them in wrecking yards.